Communication system



Patenred July 15, i941 l2,249,456

UNITED STATES PATENT Vo1-"FICE COMMUNICATION SYSTEM Richard H. Campbell, Racine, Wis., 'assignor to Webster Electric Company, Racine, Wis., a corporation ot Delaware Application March 25, 1940, SerialNo. 325,669 16 Claims. `(Cl. 179-1) The present invention relates to intercommunication systems, and particularly to intercom'- munication systems of the loudspeaking type. It has for its primary object the provision of an improved system for providing communication between various parts of a residence or the like, which parts include a plurality of locations within the residence and one or more locations exterior thereof, such as entrance ways.

The system of the present invention comprises a single amplier, a plurality'of stations within the residence and which are referred to hereinafter as central stations, each provided with a translating device consisting of. a loudspeaker adapted to be utilized both as a microphone and a receiver, a communication direction control switch and a selector switch, and a number of tively. The power switches are all connected in parallel so that closure of any one of them comstations located exteriorly of the residence and hereinafter referred to as substations, provided only with translating means oi' the previouslymentioned type.

It is a further object oi the invention to provide a system in which the previously-mentioned elements of the system are arranged so that any central station can be placed in communication with any other central station, but in which eavesdropping (listening to conversations at another station when interstation communication is not being carried on) between central stations is prevented.

Other objects and advantages of the invention will become apparent from the ensuing description, in the course of which reference is had to .the accompanying drawing, the single iigure of which represents schematically one embodiment of thev invention.

Referring now to the gure, it may be seen that the illustrated system comprises five stations numbered I to 5, inclusive. f these stations, I, 2 and 3 are central stations and 4 and 5 are substations. The central stations may be located on various floors of a house. For instance, station I may be on the first iioor, station 2 in the basement, and station 3 on the second floor, or in some other building associated with the residence, such as a garage. Stations 4 and 5 may be located at the front and rear entrance ways to the house, respectively.

Translating devices consisting of loudspeaker units adapted to be utilized both as microphones and receivers are located at each station. Thus,

the loudspeakers at stations I to 5 have been indicated by reference characters II` to I5, inclusive. The loudspeakers are preferably of the well-known permanent magnet type.

The system comprises but a single amplifier 26, which may be of any well-known construction and located at some convenient or out-ofthe-way place. It is provided with input connections 22 and output connections 24. Power pletes a power circuit to the amplier through conductor 28, conductor 26 being connected /directly to the amplier. a

Each station is also provided with a threeposition communication direction-control switch having an idle position (the uppermost position in which the switches are illustrated), a listen position (the intermediate position), and

' a talk position (the lowermost position). The

68; switch 32 includes the previously-mentioned switches are so constructed andarranged as to remain in their idle or listen positions when actuated Vthereinto and are biased for movement from the Ytalk to the listen positions. 'I'he switches at each station are so arranged with respect to the loudspeakers at the respective stations that the latter are connected to individual interstation circuits for reception of calls from other central stations or, if desired, from the substations.

The communication direction control switches at stations vI to 3, inclusive, are indicated by reference characters 42, 44 and 46, respectively. Switch 42 comprises the three simultaneously operable switch bndesfaa, so and 52; switch 44 comprises the three simultaneously operable switch blades 54, 56 and 58; and switch 46 comprises the three simultaneously operable switch blades 60, 62 and 64.

Before considering in detail the circuit connections', itmay be well to note that each of the combined selector and .power control switches likewise consists of three simultaneously operable switch blades. Switch 30 includes the previouslymentioned switch blade 36 and blades 66 and switch blade 38 and blades 1.0 and 12; and switch 34 includes the previously-mentioned switch blade 40 and blades 14 and 16.

VThe system comprises a-number of interstation conductors exceeding by three the number of stations. Each station is normally conditioned for reception of calls-the central stations by connection of the loudspeakers thereat to conductors individual to the'stations by the communication direction control switches, and the substations by direct connection. 'I'he conductors individual -to stations I to 8. inclusive. are represented by reference characters 8|` to 88, inclusive. The remaining three conductors are a ground conductor 86, which may very well be a shield for the remaining conductors, and ampliiier input and output conductors 88 and 80. Input conductor 88 is connected by a branch conductor 82 to one o! the input connection 22 of the ampliiler, the other oi' which is connected to the ground conductor by a branch conductor 84. The output-conductor 80 is connected to one oi .the vamplifier output connect-ions 24 by a branch conductor 88, the other of which is connected to ground by branch-conductor 98.

The loudspeaker II at station I is connected to the station I conductor 8| by conductor |00, switch blade 80 and conductor |02, and to ground conductor 88 by a conductor |04. Similarly. loudspeaker I2 at station 2 is connected to the station 2 conductor 82 by conductor |08, switch blade 88 and conductor |08, and to ground conductor 88 by a conductor IIO; and loudspeaker I3 at station 3 is connected to the station 8 conductor 83 by Iconductor I I2, switch blade 82 and conductor II4, and to the ground conductor by a conductor ||8.

Loudspeaker I4 at station 4 is connected directly to station 4 conductor 84 and to the ground conductor by a conductor II8: and loudspeaker I8 at station 8 is connected directly to station 8 conductor 88 and to the ground conductor by a conductor |20 and conductor |I8.

The central stations can call each other by manipulation of the communication direction control switches and the combined selector and power control switches, the selector switches being first operated to select the desired station and render operative the amplier, and thecomlmunication direction control switches being operated to the talk position. The selector switches at each station are so arranged that they can be connected to thel interstation conductors individual to the other stations. Thus, the selector switch blade 88 at station I is operable to complete the circuits to the communication direction control switch blade 82 from conductors 82 and 83, through a conductor |22 interconnecting the switch blades and branch conductors |24 and |28 leading from conductors 82 and 83, respectively.

Similarly, switch blade 10 at station 2 is operable to connect conductors 8| and 88 to communication direction control switch blade 88' through conductor |28 interconnecting the switch blades and branch conductors |30 and |82 leading from conductors 8| and 88, respectively; and selector switch blade 14 is operable to connect conductors 8| and 82 to the communication direction control switch' blade 84 through a conductor |34 interconnecting the switch blades and branch conductors I 88 and |88 leading from conductors 8| -and 82, respectively.

Operation of any of the selector switches also completes the power supply circuit to the ampliiler so that the amplifier is energized and a call may be made by operation of the communication direction control switch into" its talk position. Thus, when the communication direction control switch 42 at station I is operated into its talk position, the loudspeaker II thereat is connected to the input of the amplifier through a circuit including switch blade 5.0, which connects the loudspeaker to the input conductor 88. At the same time, switch blade 52 connects the selected central station conductor directly to the output conductor 80, it being'r'emembered that the loudspeakers at the other stations are normally connected to the interstation conductors individual to those stations. The operators at stations 2 and 8 may similarly call the operators at theA other stations by operation ot the selector and power control switch and the communication direction control switch thereat.

The called station can respond when the communication direction control switch at the calling station is returned to its listening position, and this is possible without operation oi' the selector switch thereat. Thus, assuming that station I has called station 2 andthe communication direction control switch 42 at station I has been returned to its listen position, at which time selector switch blade connects the loudspeaker II directly to the output conductor 80, the operator at station 2 can talk to station I by simply depressing the communication direction control switch 44 thereat to its talk position, wherein the loudspeaker I2 is connected directly to the input conductor 88. It may be seen, therefore, that communication may be carried on in alternate directions by alternately manipulating 'the ccmmunication direction control switches at the two stations from their listen to their talk positions.

The combined selector and power control switches at the central stations are operable into positions to connect either or both oi' substations 4 and 8 to the central station. Selective individual connection of the stations is provided, by extending branch conductors from conductors 84 and 88 to b e engaged by the selector switches in vdifferent positions thereof, and joint connection is provided by extending additional branch conductors to be engaged by the selector switches in one position thereof. Thus, conductors 84 and 88 are connected by branch conductors |40 and |42, |44 and |48, and |48 and |80, which are adapted to be engaged by switch blades 88, 10 and 14, respectively, in different positions thereof. Additional branch conductors |82 and |84, |88 and |88, and |80 and |82 are provided for simultaneous engagement by these switch blades when operated into afurther position.

To enable substations 4 and 8'to communicate with the central station, additional branch conductors are extended from conductors 84 and 88 to be engaged by switch blades 88, 12 and 18 at stations I, 2 and 8, respectively. Conductors 84 and 88 are connected by branch conductors 10,

and |12, |14 and |18, and |18 and |80, so thatA the latter may be engaged by the abovementioned switch blades in different positions thereof. Additional branch conductors |82 and I 84, |88 and |88, and |90 and |82 are provided, so that these may be engaged simultaneously when the switch blades are operated into a further position.

In order to condition any of the central stations i'or the reception oi' calls from the substations, it is necessary that the selector switches be operated to select the .desired substation or 88, conductor |48, switch blade 48, and the conductors 88 and 92, the circuit being completed through ground. The loudspeaker II at station I is connected to the'output of the ampiiler 20 The former is connected to the input through conductor |00, switch blade 50 and conductors 88 and 52, the circuitbeing completed through ground. Loudspeaker I4 is connectedto the output of the amplier through conductors Il, |40, switch blade 66, conductor |22, switch blade 52, and conductors 90 and 86, the circuit being completed through ground. Thus, alternate communication in opposite directions may be eifected by operation of the talk-listen switch 42 from its intermediate to lowerniost positions.

Communication may be similarly carried on between central station and substation 5 alone by operating' the selector switch into a position wherein switch blade 56 is in engagement with conductor |42 and switch blade 8l is in engagement with conductor |12. Central station I may communicate with both stations l and 5 by operating the selector switch into a position wherein switch blade 66 simultaneously engages conductors |52 and |54, and switch blade 68 simultaneously engages conductors |82 and |84.

The remaining central stations may-communicate with one or both the substations l and B in a similar manner through circuits that have been described in detail above.

Eavesdropping, that is, listening to conversation being carried on at station when the communication controll switch I2 thereat is in the idle position, is prevented, because in the idle position of the switch the loudspeaker at station is not connected to the'input of the amplier. It may be noted, however, that when communication is being carried on between any two of the stations, another station may listen in on the conversation. Eavesdropping is also prevented when the communication control switch at any central station is in its intermediate or listen position, because the loudspeaker at the station at this time is connected kto the output of the amplier.

It is to be noted that while only a comparatively few stations have been illustrated. in the embodiment of the invention described above, it

States Letters Patent is:

1. In an intercommunication system, the combination including, an ampliiler having input and output connections, a -plurality of stations each including aA translating device utilizable as a 'microphone and a receiver, a multi-position communication control switch and circuits controlled thereby, and interstation circuits individual to each station, said circuits and switches being so constructed and arranged that the devices at each station are connected to the interstation circuit individual to the station directly, through the switch in one position of the switch thereat and to the inputand output of the ampliner in other positions of the switch.

2. In an intercommunication system, the combination including, an amplier having input and output connections, a. plurality of stations each including a translating device utilizable as a microphone and a receiver, a multi-position communication 4control switch, a station selector switch and circuits controlled by said switches, and interstation circuits individual to each station, said circuits and communication control switches being so constructed and-arranged that -the devices at each station are connected to the `to the communication control switch at the station land thelatter is adapted in one position thereof to connect the selected circuit to the output of the ampliiier.

3. In an intercommunication system, the combination including, an ampliiier having input and output connections, a plurality of stations each including a translating device utilizable as a microphone and a receiver, a three-position communication control switch, a station selector switch and circuits controlled by said switches. and interstation circuits individual to each station, said circuits and communication control switches being so constructed and arranged that they devices at each station are connected to the interstation circuit individual to the station in a first position of the switch thereat and to the output and input of the ampliiler inv second andv third positions thereof, and said selector switches, communication control switches and circuits being so constructed and arranged that the selector switch at each station is selectively operable to connect interstation ycircuits individual to other stations to the communication control switch at the station and the latter is adapted in its third position to connect the selected circuit to the output of the amplifier.

4. In an intercommunication system, the combination including, an amplier having input and output connections, a.y plurality of stationsv each including a translating device utilizable as a microphone and a receiver, interstation circuits each terminating in a pair of branch conductors at one station and connected tothe translating devices at the other stations, a multi-position communication control switch at the one station, a selector switch at said one? station operable Aat said one station is connected to the output of the amplifier and the'y translating device at a selected other station is connected to the input V of the amplifier through one of a pair of branch conductors and in anothery position of the switch the translating device at said one station is connected to the input of the amplifier and the translating device at the selected other station is connected to the output of the ampliner through another of a pair of branch conductors.

5. In an intercommunication system, the combination including an amplifier having input and output connections, a plurality of stations each other stations, a communication control switch at said one station, selector switch means at said one station operable to connect one or more of said pairs oi' branch conductors to said communication control switch, "and circuits controlled by said communication` control switch, said switches and circuits being so constructed and arranged that in one position of said communication control switch the translating device at said one station is connected to the output of the amplier and the translating devices at the selected other stations are connected to the input of the amplifier through oneof said ,branch conductors, and in another position of the switch the translating device 4at said one station is connected to the input of the amplifier and the translatingl devices at the selected other stations are connected to the output of the amplifier through the other of said branch conductors.

6. In an intercommunication system, the combination including an ampliiler having input and output connections, a plurality of stations each including a translating device utilizable as a microphone and a receiver, a multi-position communication control switch and circuits controlled thereby, a station selector switch and circuits controlled thereby, interstation circuits individual to said stations, another station having a similar translating device, an interstation circuit to which said device is connected, said selector switches and circuits Vbeing so constructed and arranged thatsaid interstatlon circuits may be selectively connected to said communication control switches and'said communication control switches and circuits being so constructed and arranged that when one of said plurality of stations is selected ata station, the communication control switch thereat is operable to connect the translating device thereat to the output or input of the amplifier and the selected interstatlon circuit to the output of the amplifier when the translating device is connected to the input of the amplifier, and when said other station is selected the communication control switch is operable between two positions alternately to connect said translating devices to the output and input of the amplifier.

'7. In an intercommunication system, the combination including, an amplifier having'input and output connections, a plurality of stations each including a translating device utilizable as a microphone and a receiver, a multi-position communication control switch and circuits controlled thereby and a station selector switch and circuits controlled thereby, interstatlon circuits individual to said stations, a plurality of other stations having similar translating devices, interstatlon circuits to which said devices are connected at said other stations, said selector switches and circuits beiig so constructed and arranged that said interstatlon circuits may be selectively connected to the communication control switches and said communication .control switches and translating device thereat to the output or input of the ampliiler and the selected interstatlon ,circuit to the output of the amplifier when the translating device is -connected to the input of the amplifier, and when one of said other plurality of stations is selected the communication control switch is operablebetween two positions alternately to connect'said translating devices to the output and input of the ampliiler.

8. In an intercommunication system, thecoinbination including, an amplifier having input and output connections, a plurality of stations each including a translating device utilizable as a microphone and a receiver, a three-position communication control switch, and a circuit connection from said switch directly to said translating device, interstatlon circuits individual to said stations, said switch being adaptedto connect said translating device directly to the interstation circuit associated with the station in a first position and to connect the translating device directly to the output and input of the amplifier in second and third positions of the switch.

9. In an intercommunication system, the comu bination including, an am'pliiler having input and output connections, a plurality of stations each including a translatingl device. utilizable as a microphone and a receiver, a two-pole threeposition communication control switch and a station selector switch, and interstatlon conductors individual to each station, said input and output connections leading to each of said stations, a circuit connection from the selector switch to one pole of the communication control switch, a circuit connection from the translating device to the other pole of the communication control switch, said second-mentioned pole being adapted to connect said translating device directly to the interstatlon conductor individual to the station in a first position thereof, to the output circuit in a second position thereof, and to the input connection in a-third position thereof, and said first-mentioned pole being adapted to connect the selector switch to the output connection in the third position of said communication control switch. g ,n

' 10a' In an intercommunication system, the combination including, an amplifier having input and output connections, a pair of stations each including a translating device utilizable as a microphone and a receiver, an interstatlon circuit terminating in a pair of branch conductors at one station and connected to the translating device at the Vother station, atwo-pole selector switch at said one station adapted to complete circuits to said branch conductors in a predetermined position thereof, a multi-position threepole communication control switch at the one station, two of said poles being connected directly to the poles of said selector switch, the third pole oi said communication control switch being connected directly to the translating device at said one station, the poles of said communication control switch being adapted in one position to connect the translating device at one station to the output of the ampliner and one of said branch conductors to the input of the amplifier, and in another position to connect said translating device to the input of the amplifier and the other branch conductor to the output of the amplifier.

between one of said stations and the other stations, each of said circuits terminating in a pair of branch conductors at said one station'and being connected directly to the translating devices at the other-stations, a two-pole selector switch at said one station adapted simultaneously to complete circuits to said branch conductors, a multi-position three-pole communication control switch at said one station, two of said poles being connected directly to the poles of the selector switch and the third pole being connected directly to the translatng device at said one station, said communication control switch being adapted in one position thereof to connect one of said branch conductors directly to the input of the amplifier and the translating device at said one station to the output of the amplier, and in another position yto connect the other of said branch conductors directly to the output of the amplifier and the translating device to the input of the amplier.

12. In an intercommunication system, the combination including, an amplifier having input and output connections, a plurality of stations eachincluding a translating device utilizable as a microphone and a receiver, interstation circuits between one of said stations and the other stations, each of said circuits terminating in a pair of branch conductors at said `one station and being connected directly to the translating devices at the other stations, a two-pole selector switch at said one station adapted simultaneously to complete circuits to said branch conductors, a multi-position three-pole communication control switch at said one station, two of said poles being connected directly to the poles of the selector switch and the third pole being connected directly to the translating device at said one station, said communication control switch being other branch conductors extending therefrom and so arranged as to be engaged simultaneously by said poles oi the selector switch in another position thereof, whereby communication may be established between said one station andselected ones or all oi the other stations.

13. In an intercommunication system, the combination including, an amplier having input and output connections, a plurality of stations each having a translating device utilizable as a microphone and a receiver, a three-pole three-position communication control switch and a two-pole multi-position selector switch, interstation circuits individual to said stations adapted selectively to be connected to a rst pole of the communication control switch by one pole of the se- -lector switch, another station having a similar translating device, 'an interstation circuit to which said device is connected and having a pair' of branch conductors engageable by the poles of said selector switch in one position thereof. conductors leading from the two poles or the selector switch to the iirst and a second pole of the communication control switch, a conductor leading from eachof the translating devices at said plurality of stations to the third poles of the communication control switches thereat, the third pole of the communication control switch at each station being adapted to connect the translating device thereat tothe interstation circuit individual to the station in a ilrst position of the switch, and to the output and input oi the ampliiier in the second and third positions thereof, the second pole being adapted to connect the other of the two poles of the selector switch to the input in the second position thereof, and the third pole being adapted to connect the one pole of the selector switch to the output'in the third position thereof.

14'. A unit for use in an intercommunication system comprising a single amplifier and other similar units, including in combination amplifier input and output connections, a translating device utilizable as a microphone and a receiver, a communication circuit individual to the unit,y a three-position communication control switch connected directly to the translating device and adapted in a first position to connect the translating device directly to the interstation circuit,

and in other positions selectively to connect said translating device tothe input and output conl nections.l

15. A unit for use in an intercommunication system, including ampliiier input and output connections, a translating device utilizable both as a microphone and a receiver, an interstation circuitindividual to the station and interstation circuits individual to other units in the` system, a three-position two-pole communication control switch, one pole of which is directly connected to the translating device, a station selector switch adapted selectively to engage the second-mentioned interstation conductors and connected to vthe other pole of said communication control switch, said communication control switch being adapted in a rst position to connect the translating device to said 4first-mentioned interstation circuit through said one pole, in a second position to connect said device to the output connection through said one pole, and in a third position to connect said device to the input connection through said one pole, and the other pole being adapted in the third position to connect said selector switch to the output connection.

16. A unit for use in an intercommunication system, including in combination, ampliiier input and output connections, a translating device utilizable as a microphone `and a receiver, a pluralposition'three-pole communication control switch, a two-pole selector switch, an interstation con- `ductor terminating in a pair of branch conduccontrol switch, said nrst and third poles'being adapted to complete circuits to the input and output connections respectively in one position of the communication control switch and said second and'third poles being adapted to complete' circuits to the output and input connections in another position o'. the communication control switch. I

RICHARD H. CAMPBELL. 

